A variety of situations exist in which it is desirable to perform an action on the basis of sounds which may naturally occur in an ambient environment, or sounds which are specifically generated as input parameters. As an example, U.S. Pat. No. 5,536,902 discloses a system in which an output sound is synthesized in accordance with the analysis of a received input sound. That system employs a spectral modeling synthesis technique, to analyze an input sound and use the results of the analysis to generate a synthesized version of the same sound, or another sound which is related to the original input sound, e.g. one having extended or shortened duration.
It is desirable to utilize input sounds not only for the synthesis of related output sounds, but also for the control of events that are distinct from the input sounds themselves. One area of particular interest in this regard pertains to the control of synthesizers that can produce highly complex sounds. An example of such a synthesizer is the model VL-1 Virtual Tone Generator, manufactured by Yamaha Corporation. This synthesizer uses mathematical physical models of instruments to generate sounds. Although the synthesizer is capable of generating extremely realistic sounds, it is also difficult to control accurately, due to the nature of the physical model synthesis technique. In particular, the synthesizer has a number of parameters, each of which is controllable in real time to affect the sound synthesis in various ways and to different degrees. These various parameters include: Pressure, Embouchure, Pitch Bend, Vibrato, Tonguing, Amplitude, Scream, Breathe Noise, Growl, Throat Formant, Dynamic Filter, Harmonic Enhancement, Damping and Absorption. The synthesizer permits a single input controller to change any number of these synthesis parameters. In addition, the synthesis parameters can be associated with control curves, or functions, that are applied to the associated controller input parameters.
One approach for controlling a synthesizer of this type is described in a copending application of Adams et al entitled "System and Method for Controlling a Music Synthesizer". This approach maps manually generated signals, such as finger pressure on sensor devices, to input parameters that control the operation of the synthesizer. It is an objective of the present invention to utilize input sound as the basis for the parameters that control the synthesizer, rather than finger pressure or the like, because sounds offer greater dimensionality and dynamic range than many types of manually generated signals.
In the past, the analysis of sounds to determine control parameters has been principally based upon the pitch of the input sound. In essence, pitch is a measure of the periodicity of a sound. For low frequency sounds, therefore, a relatively large number of input samples must be taken to determine the pitch. This requirement means there is a natural latency in the analysis of the sound. Due to delays which may be inherent in such an approach, the control of the desired output event is not immediately responsive to the input data, from a perceptual standpoint. For instance, there may be gaps in a synthesized output sound until enough input data is obtained to determine the pitch. This phenomenon is evident, for instance, in cases where the input sound that is used to control an event is a speaker's voice.
Accordingly, it is an objective of the present invention to provide a technique for analyzing sounds to determine parameters other than pitch which enable the analysis to be accomplished more quickly, and thereby provide responsive control of output events. In particular, it is an objective to provide a technique that provides for perceptually immediate response to voice-based input controls.